Commit 22f12179 authored by David Stenberg's avatar David Stenberg
Browse files

[SelectionDAG] Salvage debug info for non-constant ADDs (2nd try) (#68981) 



Teach SelectionDAG::salvageDebugInfo() to salvage debug information for
ADD nodes where the RHS is non-constant.

In the first try, the test case used the MIR output that was produced by
using -stop-before=sparc-isel. Running -start-before=sparc-isel on that
output resulted in the following verifier error with EXPENSIVE_CHECKS:

  "Function has NoVRegs property but there are VReg operands".

In this re-attempt the test case has been rewritten to a .ll test by
extracting the IR from the original MIR file. The test still starts
before sparc-isel.

Co-authored-by: default avatarMikael Holmen <mikael.holmen@ericsson.com>
parent cc2fbc64

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

+33 −10
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ 
#include "llvm/Analysis/MemoryLocation.h"

#include "llvm/Analysis/ValueTracking.h"

#include "llvm/Analysis/VectorUtils.h"

#include "llvm/BinaryFormat/Dwarf.h"

#include "llvm/CodeGen/Analysis.h"

#include "llvm/CodeGen/FunctionLoweringInfo.h"

#include "llvm/CodeGen/ISDOpcodes.h"
@@ -10843,8 +10844,11 @@ void SelectionDAG::salvageDebugInfo(SDNode &N) { 
    case ISD::ADD: {

      SDValue N0 = N.getOperand(0);

      SDValue N1 = N.getOperand(1);

      if (!isa<ConstantSDNode>(N0) && isa<ConstantSDNode>(N1)) {

        uint64_t Offset = N.getConstantOperandVal(1);

      if (!isa<ConstantSDNode>(N0)) {

        bool RHSConstant = isa<ConstantSDNode>(N1);

        uint64_t Offset;

        if (RHSConstant)

          Offset = N.getConstantOperandVal(1);



        // Rewrite an ADD constant node into a DIExpression. Since we are

        // performing arithmetic to compute the variable's *value* in the
@@ -10853,7 +10857,8 @@ void SelectionDAG::salvageDebugInfo(SDNode &N) { 
        auto *DIExpr = DV->getExpression();

        auto NewLocOps = DV->copyLocationOps();

        bool Changed = false;

        for (size_t i = 0; i < NewLocOps.size(); ++i) {

        size_t OrigLocOpsSize = NewLocOps.size();

        for (size_t i = 0; i < OrigLocOpsSize; ++i) {

          // We're not given a ResNo to compare against because the whole

          // node is going away. We know that any ISD::ADD only has one

          // result, so we can assume any node match is using the result.
@@ -10861,19 +10866,37 @@ void SelectionDAG::salvageDebugInfo(SDNode &N) { 
              NewLocOps[i].getSDNode() != &N)

            continue;

          NewLocOps[i] = SDDbgOperand::fromNode(N0.getNode(), N0.getResNo());

          if (RHSConstant) {

            SmallVector<uint64_t, 3> ExprOps;

            DIExpression::appendOffset(ExprOps, Offset);

            DIExpr = DIExpression::appendOpsToArg(DIExpr, ExprOps, i, true);

          } else {

            // Convert to a variadic expression (if not already).

            // convertToVariadicExpression() returns a const pointer, so we use

            // a temporary const variable here.

            const auto *TmpDIExpr =

                DIExpression::convertToVariadicExpression(DIExpr);

            SmallVector<uint64_t, 3> ExprOps;

            ExprOps.push_back(dwarf::DW_OP_LLVM_arg);

            ExprOps.push_back(NewLocOps.size());

            ExprOps.push_back(dwarf::DW_OP_plus);

            SDDbgOperand RHS =

                SDDbgOperand::fromNode(N1.getNode(), N1.getResNo());

            NewLocOps.push_back(RHS);

            DIExpr = DIExpression::appendOpsToArg(TmpDIExpr, ExprOps, i, true);

          }

          Changed = true;

        }

        (void)Changed;

        assert(Changed && "Salvage target doesn't use N");



        bool IsVariadic =

            DV->isVariadic() || OrigLocOpsSize != NewLocOps.size();



        auto AdditionalDependencies = DV->getAdditionalDependencies();

        SDDbgValue *Clone = getDbgValueList(DV->getVariable(), DIExpr,

                                            NewLocOps, AdditionalDependencies,

                                            DV->isIndirect(), DV->getDebugLoc(),

                                            DV->getOrder(), DV->isVariadic());

        SDDbgValue *Clone = getDbgValueList(

            DV->getVariable(), DIExpr, NewLocOps, AdditionalDependencies,

            DV->isIndirect(), DV->getDebugLoc(), DV->getOrder(), IsVariadic);

        ClonedDVs.push_back(Clone);

        DV->setIsInvalidated();

        DV->setIsEmitted();

llvm/test/DebugInfo/Sparc/pointer-add-unknown-offset-debug-info.ll

0 → 100644
+54 −0
Original line number Diff line number Diff line 
; NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 3

; RUN: llc -mtriple=sparcv9 %s -start-before=sparc-isel -o - -stop-after=sparc-isel | FileCheck %s



target datalayout = "E-m:e-i64:64-n32:64-S128"

target triple = "sparcv9"



define void @pointer_add_unknown_offset(ptr %base, i32 %offset) !dbg !7 {

  ; CHECK-LABEL: name: pointer_add_unknown_offset

  ; CHECK: bb.0.entry:

  ; CHECK-NEXT:   liveins: $i0, $i1

  ; CHECK-NEXT: {{  $}}

  ; CHECK-NEXT:   [[COPY:%[0-9]+]]:i64regs = COPY $i1

  ; CHECK-NEXT:   [[COPY1:%[0-9]+]]:i64regs = COPY $i0

  ; CHECK-NEXT:   [[SRAri:%[0-9]+]]:i64regs = SRAri [[COPY]], 0

  ; CHECK-NEXT:   [[SLLXri:%[0-9]+]]:i64regs = SLLXri killed [[SRAri]], 2

  ; CHECK-NEXT:   DBG_VALUE_LIST !13, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_stack_value), [[COPY1]], [[SLLXri]], debug-location !16

  ; CHECK-NEXT:   DBG_VALUE_LIST !14, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus, DW_OP_plus_uconst, 3, DW_OP_stack_value), [[COPY1]], [[SLLXri]], debug-location !16

  ; CHECK-NEXT:   DBG_VALUE_LIST !15, !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 2, DW_OP_plus, DW_OP_LLVM_arg, 1, DW_OP_LLVM_arg, 3, DW_OP_plus, DW_OP_plus, DW_OP_stack_value), [[COPY1]], [[COPY1]], [[SLLXri]], [[SLLXri]], debug-location !16

  ; CHECK-NEXT:   [[ORri:%[0-9]+]]:intregs = ORri $g0, 42

  ; CHECK-NEXT:   STrr [[COPY1]], killed [[SLLXri]], killed [[ORri]] :: (store (s32) into %ir.add.ptr)

  ; CHECK-NEXT:   RETL 8

entry:

  %idx.ext = sext i32 %offset to i64

  %add.ptr = getelementptr inbounds i32, ptr %base, i64 %idx.ext

  call void @llvm.dbg.value(metadata ptr %add.ptr, metadata !13, metadata !DIExpression()), !dbg !16

  call void @llvm.dbg.value(metadata ptr %add.ptr, metadata !14, metadata !DIExpression(DW_OP_plus_uconst, 3, DW_OP_stack_value)), !dbg !16

  call void @llvm.dbg.value(metadata !DIArgList(ptr %add.ptr, ptr %add.ptr), metadata !15, metadata !DIExpression(DW_OP_LLVM_arg, 0, DW_OP_LLVM_arg, 1, DW_OP_plus)), !dbg !16

  store i32 42, ptr %add.ptr, align 4

  ret void

}



declare void @llvm.dbg.value(metadata, metadata, metadata)



!llvm.dbg.cu = !{!0}

!llvm.module.flags = !{!2, !3, !4, !5}

!llvm.ident = !{!6}



!0 = distinct !DICompileUnit(language: DW_LANG_C11, file: !1, producer: "clang", isOptimized: true, runtimeVersion: 0, emissionKind: FullDebug, splitDebugInlining: false, nameTableKind: None)

!1 = !DIFile(filename: "test.c", directory: "/tmp", checksumkind: CSK_MD5, checksum: "4321633e52cefeee6e307c697a82574f")

!2 = !{i32 7, !"Dwarf Version", i32 5}

!3 = !{i32 2, !"Debug Info Version", i32 3}

!4 = !{i32 1, !"wchar_size", i32 4}

!5 = !{i32 7, !"debug-info-assignment-tracking", i1 true}

!6 = !{!"clang"}

!7 = distinct !DISubprogram(name: "pointer_add_unknown_offset", scope: !1, file: !1, line: 1, type: !8, scopeLine: 1, flags: DIFlagPrototyped | DIFlagAllCallsDescribed, spFlags: DISPFlagDefinition | DISPFlagOptimized, unit: !0, retainedNodes: !12)

!8 = !DISubroutineType(types: !9)

!9 = !{null, !10, !11}

!10 = !DIDerivedType(tag: DW_TAG_pointer_type, baseType: !11, size: 64)

!11 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)

!12 = !{!13, !14, !15}

!13 = !DILocalVariable(name: "p", scope: !7, file: !1, line: 2, type: !10)

!14 = !DILocalVariable(name: "q", scope: !7, file: !1, line: 2, type: !10)

!15 = !DILocalVariable(name: "r", scope: !7, file: !1, line: 2, type: !10)

!16 = !DILocation(line: 0, scope: !7)